1. Field of the Invention
The present invention relates to a substrate for a cell culture, a method for fabricating such a substrate, and a method for forming cell arrangements using such a substrate.
2. Description of the Related Art
At present the culture of cells of various animals or plants is being carried out, and methods for culturing new cells are being developed. Cell culture technology is being used for the elucidation of the chemical phenomena and properties of cells, and for the examination of the physiology and poisonous properties of artificially synthesized chemicals.
Some types of cells, particularly many animal cells, adhere to something, have an adhesion dependency for growing, and cannot live for a long time in a floating condition outside of a living body. For the culturing of these types of cells having an adhesion dependency, a carrier is necessary for cell adhesion. In general, a plastic type of culture dish is used in which a cell bonding protein, such as collagen or fibronectine, is uniformly applied. It is known that the cell bonding protein acts on the culturing cells, makes the cell adhesion easy, and has an effect on the shape of the cells.
On the other hand, technology has been reported for producing certain arrangements of culture cells by making the culture cells adhere to an ultra-small area of a substrate. By using this type of technology, culture cells have possible applications such as artificial internal organs, biosensors, and bioreactors. As a method for the arrangement of culture cells, use is made of a substrate that has a patterned surface upon which the ease of adhesion differs with respect to a cell. An arrangement of cells is achieved by culturing cells on this surface and by allowing the cells to adhere only on the surface processed for the cells to adhere to.
For example, in Japanese Patent Application Kokai Publication No. Hei. 2-245181, for the purpose of breeding nerve cells in the form of a circuit, a culture cell is used as a charge storage medium that has been formed by electrostatic patterning. Further, in Japanese Patent Application Kokai Publication No. Hei. 3-7576, trials have been made of arranging culture cells on a patterned surface by a photolithographic method using a cell adhesive or a cell nonadhesive photosensitive hydrophilic polymer. Further, as reported in Japanese Patent Application Kokai Publication No. Hei. 3-7577, cell adhesive groups have been introduced into cell culture material having a cell nonadhesive surface and cell adhesive functional groups induced by irradiating it with ultraviolet light or radiation. Then, adhesive or nonadhesive monomers are applied on top of this, the surface is patterned, and, in this way, the arrangement of the cells is controlled.
Furthermore, Japanese Patent Application Kokai Publication No. Hei. 5-176753 reports on a substrate for cell culture that is patterned with collagen that has an effect on the cell attaching efficiency and form, and on a method for fabricating the substrate using photolithography. By culturing cells on such a substrate, many cells attach to collagen that has been patterned into the surface, and patterning of the cells is realized.
In conventional substrates for cell culture used for the formation of cell arrangements, the cell adhesivity of the substrate surface is fixed. That is, it has not been possible to change the cell adhesion surface of a prepared substrate to a nonadhesive surface, or conversely, to change the cell nonadhesive surface to a cell adhesive surface. Also, it has been extremely difficult to obtain more than two arrangements of cells with the conventional substrates for cell culture.